Two-dimensional grating preparation method, interference type exposure system and two-dimensional grating

Abstract

The invention discloses a two-dimensional grating preparation method, an interference type exposure system and a two-dimensional grating, and relates to the technical field of grating manufacturing, and the method comprises the following steps: under the condition that an exposure substrate is in a first pose, exposing the exposure substrate along a first direction with a first exposure dose through an interference exposure field; and under the condition that the exposure substrate is in a second pose, exposing the exposure substrate along a second direction by using a second exposure dose through the interference exposure field to obtain the two-dimensional grating. Therefore, the first exposure dose and the second exposure dose of the interference exposure field on at least one exposure position of the exposure substrate are different, so that the finally obtained two-dimensional grating has a rotation angle on a grating structure corresponding to the exposure position; therefore, grating parameters of grating structures formed at other exposure positions with the same first exposure dose and second exposure dose on the exposure substrate are different, and the preparation of the two-dimensional grating with variable grating structure parameters is realized.

Description

Technical Field

[0001] This application relates to the technical field of grating manufacturing, and more specifically, to a method for preparing a two-dimensional grating, an interferometric exposure system, and a two-dimensional grating. Background Art

[0002] The two-dimensional grating structure is a commonly used optical diffraction device in the field of Augmented Reality (AR). The unit structure parameters of the two-dimensional grating structure (such as unit shape, height, rotation angle, and duty cycle, etc.) have a direct impact on the optical diffraction characteristics of the grating.

[0003] Currently, the electron beam direct writing lithography technology is used to prepare a two-dimensional grating structure with variable grating unit structures. However, due to its high cost and low output efficiency, it is difficult to play its advantages in the manufacture of large-area grating structures. Therefore, there is an urgent need for a high-efficiency method for preparing a grating with variable grating unit parameters. Summary of the Invention

[0004] This application proposes a method for preparing a two-dimensional grating, an interferometric exposure system, and a two-dimensional grating to improve the above defects.

[0005] In a first aspect, an embodiment of this application provides a method for preparing a two-dimensional grating, which is applied to an interferometric exposure system. The interferometric exposure system includes an exposure substrate and an interferometric exposure component. The method includes: when the exposure substrate is in a first pose, using the interferometric exposure component to expose the exposure substrate along a first direction with a first exposure dose; when the exposure substrate is in a second pose, using the interferometric exposure component to expose the exposure substrate along a second direction with a second exposure dose to obtain a two-dimensional grating; where the first exposure dose and the second exposure dose are different at at least one exposure position of the exposure substrate, so that the grating structure of the two-dimensional grating corresponding to the exposure position has a rotation angle.

[0006] In a second aspect, an embodiment of this application further provides an interferometric exposure system, including an exposure substrate, a light source, and an interferometric exposure component. The light source is used to form the interferometric exposure field, and the interferometric exposure component is used to execute the method as described above.

[0007] In a third aspect, an embodiment of this application further provides a two-dimensional grating. The two-dimensional grating is manufactured based on the above method for preparing a two-dimensional grating, and the duty cycle parameters and rotation angle parameters of the two-dimensional grating along the first direction are different from each other, and the duty cycle parameters and rotation angle parameters of the two-dimensional grating along the second direction are different from each other.

[0008] Therefore, a method for preparing a two-dimensional grating, an interferometric exposure system, and a two-dimensional grating provided by this application. The method for preparing a two-dimensional grating is applied to an interferometric exposure system, and the light source is used to form an interference exposure field. The method includes: when the exposure substrate is in a first pose, exposing the exposure substrate along a first direction through the interference exposure field with a first exposure dose; when the exposure substrate is in a second pose, exposing the exposure substrate along a second direction through the interference exposure field with a second exposure dose to obtain a two-dimensional grating. Therefore, the method for preparing a two-dimensional grating provided by this application makes the first exposure dose and the second exposure dose different at at least one exposure position of the interference exposure field on the exposure substrate, so that the grating structure of the finally obtained two-dimensional grating has a rotation angle corresponding to the exposure position, thereby having different grating parameters from the grating structures formed at other exposure positions on the exposure substrate where the first exposure dose and the second exposure dose are the same, realizing the preparation of a two-dimensional grating with variable grating structure parameters.

[0009] Other features and advantages of the embodiments of this application will be described in the subsequent description. Moreover, some of them will become obvious from the description or be understood by implementing the embodiments of this application. The objectives and other advantages of the embodiments of this application can be achieved and obtained through the structures specifically pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] To more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of this application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0011] Figure 1 Shows a flowchart of a method for preparing a two-dimensional grating according to an embodiment of this application.

[0012] Figure 2 Shows a coordinate diagram of the exposure dose period curve of an interference exposure field in an embodiment of this application.

[0013] Figure 3 Shows a schematic diagram of the relationship between the exposure dose of an interference exposure field at an exposure position and the grating structure of the two-dimensional grating corresponding to the exposure position formed by the exposure.

[0014] Figure 4 Shows a schematic diagram of the relationship between the exposure dose of another interference exposure field at an exposure position and the grating structure of the two-dimensional grating corresponding to the exposure position formed by the exposure.

[0015] Figure 5 Another flowchart of the method for preparing a two-dimensional grating according to an embodiment of the present application is shown.

[0016] Figure 6 A schematic flowchart of the process of exposing an exposure substrate by an interference exposure field according to an embodiment of the present application is shown.

[0017] Figure 7 A schematic diagram of the grating structure of a two-dimensional grating formed by exposure on an exposure substrate according to an embodiment of the present application is shown.

[0018] Figure 8 A schematic diagram of the structure of an interference exposure system provided by an embodiment of the present application is shown. Detailed implementation manners

[0019] In order to enable those skilled in the art to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Usually, the components of the embodiments of the present application described and shown in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application to be protected, but only represents the selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts belong to the scope of protection of the present application.

[0020] It should be noted that similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of the present application, the terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0021] Please refer to Figure 1 , Figure 1 A method flowchart of a method for preparing a two-dimensional grating according to an embodiment of the present application is shown. The method is applied to an interference exposure system as shown in Figure 7 . The interference exposure system includes an exposure substrate and a light source. The light source is used to form an interference exposure field. The method includes the following steps:

[0022] S110: When the exposure substrate is in the first pose, expose the exposure substrate along the first direction with the first exposure dose through the interference exposure field.

[0023] In this embodiment, the exposure substrate is a substrate coated with photoresist. The light source is used to emit two or more coherent light beams. After the multiple coherent light beams propagate along different paths, they interfere on the plane where the exposure substrate is located to form an interference exposure field. Taking the interference of two collimated coherent light beams on the exposure substrate as an example, a periodic one-dimensional fringe will be generated in the formed interference exposure field, and the optical power along the normal direction of the fringe in the interference exposure field shows a periodic sine change. And the change in optical power corresponds to the change in the exposure dose of the interference exposure field. Therefore, as Figure 2 shown, Figure 2 FIG. shows a coordinate diagram of the exposure dose period curve of an interference exposure field in an embodiment of the present application. The X-axis represents the coordinate along the normal direction of the fringe, and the Y-axis represents the exposure dose value corresponding to the coordinate point on the X-axis. It can be seen that the exposure dose value of the interference exposure field along the normal direction of the fringe also shows a periodic sine change. Exemplarily, the photoresist on the exposure substrate is positive photoresist. Then, under the action of the interference exposure field, the photoresist is etched, and the greater the exposure dose, the greater the degree of exposure and etching of the photoresist on the substrate. Therefore, when using the interference exposure system to perform interference exposure on the exposure substrate, a grating structure corresponding to the exposure dose of the interference exposure field will be formed on the exposure substrate under the action of the interference exposure field.

[0024] In this embodiment, the first pose is used to characterize a pose form of the exposure substrate placed in the interference exposure field. The first exposure dose is used to characterize the exposure dose periodic curve corresponding to the interference exposure fringes used for exposure in the interference exposure field when the exposure substrate is in the first pose. That is, the magnitude of the first exposure dose can refer to the peak magnitude of the exposure dose that periodically changes at the first pose in the interference exposure field. And the first direction is used to characterize the normal direction of the interference exposure fringes formed by the interference exposure field. Exemplarily, if a plane rectangular coordinate system is established with an arbitrary point on the plane as the origin in the plane where the exposure substrate is located, the first direction can refer to the direction of the X-axis or the Y-axis in the plane rectangular coordinate system. Therefore, according to the above analysis, when the exposure substrate is placed in the interference exposure field in the first pose and exposed along the first direction with the first exposure dose, a one-dimensional grating structure with grating parameter characteristics corresponding to the interference exposure fringes with the first exposure dose will be formed on the exposure substrate, and the formed grating structure is periodically distributed along the first direction.

[0025] S120: In the case where the exposure substrate is in the second pose, expose the exposure substrate along the second direction with the second exposure dose through the interference exposure field to obtain a two-dimensional grating.

[0026] In this embodiment, the second pose is used to characterize another pose form of the exposure substrate placed in the interference exposure field, which is different from the first pose. The second exposure dose is used to characterize the exposure dose periodic curve corresponding to the interference exposure field for exposure when the exposure substrate is in the second pose, and the magnitude of the second exposure dose can refer to the peak magnitude of the exposure dose that periodically changes at the second pose of the interference exposure field. Therefore, when the exposure substrate is exposed along the first direction by the interference exposure field with the first exposure dose at the first pose and then moved to the second pose and exposed along the second direction by the interference exposure field with the second exposure dose, a two-dimensional grating will be formed. Moreover, it can be understood that there are multiple exposure positions on the exposure substrate, and each exposure position has a one-to-one correspondence with the grating structure formed on the two-dimensional grating. The grating parameters of a certain grating structure will be jointly determined by the first exposure dose and the second exposure dose of the interference exposure field corresponding to the exposure position of the grating structure. Further, the grating structure corresponding to an exposure position can refer to a grating unit or a grating region including multiple grating units.

[0027] Further, make the first exposure dose and the second exposure dose different at at least one exposure position of the exposure substrate by the interference exposure field. That is to say, when the exposure substrate is exposed along the first direction by the interference exposure field, the first exposure dose at one exposure position is different from the second exposure dose at the same exposure position when the exposure substrate is exposed along the second direction by the interference exposure field, so that the grating structure of the two-dimensional grating corresponding to this exposure position has a rotation angle. Specifically, reference can be made to Figure 3 , Figure 3 shows a schematic diagram of the relationship between the exposure dose of an interference exposure field in an exposure position and the grating structure of the two-dimensional grating formed by its exposure corresponding to the exposure position. Among them, Figure 3 a is a graph of the exposure dose of an interference exposure field when exposing the exposure substrate along the first direction at the exposure position, Figure 3 b is a graph of the exposure dose of an interference exposure field when exposing the exposure substrate along the second direction at the exposure position, Figure 3 c is Figure 3 a and Figure 3 b shows a schematic diagram of the grating structure corresponding to the exposure position obtained after exposure by an interference exposure field. Exemplarily, Figure 3 the grating structure shown in c is a grating region including multiple grating units. It can be seen that when the exposure dose of the interference exposure field for exposure along the first direction is equal to the exposure dose of the interference exposure field for exposure along the second direction, the grating structure corresponding to the exposure position obtained is a two-dimensional grating structure with periodic characteristics in the first direction and the second direction; among them, Figure 3d is the exposure dose curve diagram at the exposure position when another interference exposure field exposes the exposure substrate along the first direction. Figure 3 e is the exposure dose curve diagram at the exposure position when another interference exposure field exposes the exposure substrate along the second direction. Figure 3 f is another Figure 3 d and Figure 3 The schematic diagram of the grating structure corresponding to the exposure position obtained after exposing with the interference exposure field shown in e. Exemplarily, Figure 3 The grating structure shown in f is also a grating region including multiple grating units. According to the above analysis, the exposure dose used when exposing along the first direction mainly determines the grating structure along the first direction, and the exposure dose used when exposing along the second direction mainly determines the grating structure along the second direction. That is to say, if the exposure doses of the interference exposure field for exposure along the first direction and the interference exposure field for exposure along the second direction are not equal, it will cause the grating structure formed in the first direction corresponding to the exposure position to be uneven with the grating structure formed in the second direction, and finally the grating structure of the two-dimensional grating will rotate. Combining Figure 3 a- Figure 3 c with Figure 3 d- Figure 3 f, it can be seen that Figure 3 The exposure dose in e is relatively Figure 3 smaller than the exposure dose in d, and the formed two-dimensional grating structure Figure 3 f compared to the two-dimensional grating structure Figure 3 c formed under the condition of equal exposure dose, has rotated by a certain angle. Therefore, by making the first exposure dose and the second exposure dose of the interference exposure field at the exposure position of the exposure substrate different, the grating structure formed by the two-dimensional grating at the position corresponding to this exposure position can have a rotation angle.

[0028] Furthermore, according to the above analysis, the ratios of the first exposure dose and the second exposure dose of the interference exposure field at the exposure position are different, and finally the magnitudes of the rotation angles of the grating structures formed by the obtained two-dimensional gratings corresponding to this exposure position are also different. Therefore, when the first exposure dose and the second exposure dose used for exposing different exposure positions on the exposure substrate are different, two-dimensional gratings with different rotation angle structure parameters of the grating structure can be obtained. Further, when the grating structure is a grating region including multiple grating units, by regulating the first exposure dose and the second exposure dose of the interference exposure field at different exposure positions, the zoning regulation of the rotation angle parameters of the two-dimensional grating can be realized.

[0029] Therefore, a method for fabricating a two-dimensional grating provided by an embodiment of the present application is applied to an interference exposure system. The interference exposure system includes an exposure substrate and a light source, and the light source is used to form an interference exposure field. The method includes: when the exposure substrate is in a first pose, exposing the exposure substrate along a first direction through the interference exposure field with a first exposure dose; when the exposure substrate is in a second pose, exposing the exposure substrate along a second direction through the interference exposure field with a second exposure dose to obtain a two-dimensional grating. By making the first exposure dose and the second exposure dose different at at least one exposure position of the exposure substrate in the interference exposure field, the grating structure corresponding to the exposure position of the finally obtained two-dimensional grating has a rotation angle, so that the grating parameters of the grating structure formed at other exposure positions on the exposure substrate with the same first exposure dose and second exposure dose are different, realizing the fabrication of a two-dimensional grating with variable grating structure parameters.

[0030] Please refer to Figure 5 , Figure 5 which shows a flowchart of another method for fabricating a two-dimensional grating according to an embodiment of the present application. The method is applied to Figure 8 the interference exposure system shown in

[0031] S210: Adjust the magnitude of the first exposure dose or the second exposure dose of the interference exposure field at at least one exposure position of the exposure substrate to adjust the structural parameters of the grating structure of the two-dimensional grating corresponding to the exposure position.

[0032] In this embodiment, refer to Figure 4 , Figure 4 which shows a schematic diagram of the relationship between the exposure dose of another interference exposure field at an exposure position and the grating structure of the two-dimensional grating formed by the exposure. Among them, Figure 4 a is a graph of the exposure dose at the exposure position when another interference exposure field exposes the exposure substrate along the first direction, Figure 4 b is a graph of another exposure dose at the exposure position when another interference exposure field exposes the exposure substrate along the second direction, Figure 4 c is another Figure 4 a and Figure 4 b are used to show the schematic diagram of the grating structure corresponding to the exposure position after exposure of the interference exposure field. Exemplarily, Figure 4 the grating structure shown in c is a grating region including multiple grating units. Specifically, the positive photoresist will be removed after exposure. More photoresist is removed in the area with a larger exposure dose, and less photoresist is removed in the area with a smaller exposure dose. Combining Figure 3 a - Figure 3 c and Figure 4 a -Figure 4 As can be seen from the comparison with c, Figure 4 a and Figure 4 the exposure dose in b is overall smaller than Figure 3 a and Figure 3 the exposure dose in b. Therefore, Figure 4 compared with Figure 3 c, the amount of photoresist removed is less, and more solid structures (the shaded areas in the figure) are left. The duty cycle is defined as the ratio of the area of the solid structure in each unit on the grating to the unit area. That is to say, when the exposure dose of the interference exposure field for exposure in the first direction is equal to the exposure dose of the interference exposure field for exposure in the second direction, but there is an overall peak change in the exposure doses in the two directions, the duty cycle of the obtained grating structure will change accordingly. Therefore, the magnitude of the exposure dose value will affect the duty cycle of the two-dimensional grating.

[0033] Therefore, in this embodiment, the first exposure dose and the second exposure dose of the interference exposure field are variable. Referring to the description in the above embodiment, it can be known that the grating structure parameters of the two-dimensional grating formed on the exposure substrate will be related to the first exposure dose and the second exposure dose at the exposure position corresponding to the grating structure. Therefore, the grating structure parameters formed by interference exposure can be changed by adjusting the magnitude of the first exposure dose or the magnitude of the second exposure dose. When the grating structure is a grating region of multiple grating units, by adjusting the magnitude of the first exposure dose or the magnitude of the second exposure dose at the corresponding exposure position, the zoning control of the grating parameters of the two-dimensional grating can be achieved.

[0034] As an implementation manner, the method for adjusting the first exposure dose or the second exposure dose of the interference exposure field at at least one exposure position on the exposure substrate can be to adjust the exposure power of the interference exposure field at the exposure position and the exposure time of the substrate in the interference exposure field to adjust the magnitude of the exposure dose at the exposure position. Specifically, the exposure dose = exposure power * exposure time. Therefore, the method for increasing the first exposure dose can be to increase the exposure power of the interference exposure field at the exposure position when the exposure substrate is at the first pose under the premise that the exposure time remains unchanged, or to increase the exposure time of the exposure substrate at the first pose in the interference exposure field under the premise that the exposure power of the interference exposure field at the exposure position remains unchanged, or to increase both the exposure power and the exposure power simultaneously. Similarly, the method for increasing the second exposure dose is similar to the above and will not be elaborated here.

[0035] As an implementation manner, the structure parameters of the two-dimensional grating include duty cycle parameters. Thus, the total magnitude of the first exposure dose and the second exposure dose at the exposure position can be adjusted to adjust the duty cycle parameter of the grating structure formed corresponding to the exposure position. Combining the analysis in the above embodiment and referring to Figure 3 and Figure 4It can be seen that the magnitudes of the first exposure dose and the second exposure dose can affect the duty cycle parameter of the two-dimensional grating. Further, as the values of the first exposure dose and the second exposure dose decrease, the amount of positive photoresist that interference exposure can remove is less, and the more solid structures remain on the exposure substrate. According to the definition that the grating duty cycle is equal to the ratio of the area of the solid structure in each unit of the grating to the unit area, that is to say, if the interference exposure field is exposed along the first direction with a lower first exposure dose and then exposed again along the second direction with a lower second exposure dose, the duty cycle parameter of the obtained two-dimensional grating is larger. Conversely, similarly, as the values of the first exposure dose and the second exposure dose increase, the duty cycle parameter of the obtained two-dimensional grating is larger. Thus, by adjusting the magnitudes of the first exposure dose and the second exposure dose that the interference exposure field has at at least one exposure position, the duty cycle parameter of the grating structure formed corresponding to the exposure position can be adjusted. Further, when the grating structure refers to a grating region including multiple grating units, by adjusting the magnitudes of the first exposure dose and the second exposure dose that the interference exposure field has at multiple different exposure positions, the zonal regulation of the duty cycle parameter of the two-dimensional grating can be achieved.

[0036] As an implementation manner, the structural parameters of the two-dimensional grating include a rotation angle parameter. The ratio of the first exposure dose or the second exposure dose at the exposure position can be adjusted to adjust the rotation angle parameter of the grating structure formed corresponding to the exposure position. Combining the analysis in the above embodiments and referring to Figure 3 It can be seen that the magnitudes of the first exposure dose and the second exposure dose can also affect the rotation angle parameter of the two-dimensional grating. Specifically, if the interference exposure field is exposed along the first direction with a higher first exposure dose and then exposed along the second direction with a lower second exposure dose, the grating unit structure on the obtained two-dimensional grating shows a clockwise rotation with respect to the reference grating unit structure, and the rotation angle is related to the difference between the first exposure dose and the second exposure dose; if the interference exposure field is exposed along the first direction with a lower first exposure dose and then exposed along the second direction with a higher second exposure dose, the grating unit structure on the obtained two-dimensional grating shows a counterclockwise rotation with respect to the reference grating unit structure, and the rotation angle is related to the difference between the first exposure dose and the second exposure dose. Exemplarily, the reference grating unit structure is the grating unit structure formed by exposure when the ratio relationship between the first exposure dose and the second exposure dose is 1. Thus, by adjusting the ratio of the first exposure dose and the second exposure dose that the interference exposure field has at at least one exposure position, the rotation angle parameter of the grating structure formed corresponding to the exposure position can be adjusted. Further, when the grating structure refers to a grating region including multiple grating units, by adjusting the ratio of the first exposure dose and the second exposure dose that the interference exposure field has at multiple different exposure positions, the zonal regulation of the rotation angle parameter of the two-dimensional grating can be achieved.

[0037] As an implementation manner, if it is desired to change the duty cycle parameter of the two-dimensional grating with the change of the first exposure dose or the second exposure dose without changing the rotation angle parameter of the two-dimensional grating, the ratio relationship between the first exposure dose and the second exposure dose can be set to 1. On this premise, by synchronously adjusting the values of the first exposure dose and the second exposure dose, it is possible to change only the duty cycle parameter of the two-dimensional grating without changing the rotation angle parameter.

[0038] As an implementation manner, the interference exposure field is formed by the interference of Gaussian beams. Such an interference exposure field has the characteristics that the exposure power at the center point is the highest, and the exposure power along the radial direction from the center point follows a Gaussian distribution. Moreover, the second direction is orthogonal to the first direction. According to the content of the above embodiments, if a plane rectangular coordinate system is established with any point in the plane where the exposure substrate is located as the origin, when the first direction refers to the direction of the X-axis in the plane rectangular coordinate system, the second direction can refer to the direction of the Y-axis in the plane rectangular coordinate system. Specifically, please refer to Figure 6 , Figure 6 shows a schematic flow chart of an exposure substrate being exposed by an interference exposure field in an embodiment of the present application. In Figure 6 , the interference exposure field 401 is an interference exposure field with a Gaussian distribution. After the exposure substrate 402 is exposed once by the interference exposure field 401 along the first direction X at the first pose 403, it is moved to the second pose 404 and then exposed twice by the interference exposure field 401 along the second direction Y, thereby obtaining a two-dimensional grating. Since the interference exposure field 401 is an interference exposure field with an exposure power following a Gaussian distribution, and there is a proportional relationship between the exposure dose and the exposure power, therefore, the first exposure dose used during the exposure at the first pose 403 decreases in a divergent manner along the first direction X, and the second exposure dose used during the exposure at the second pose 404 decreases in a divergent manner along the second direction Y. Under the two exposures of the first exposure dose that gradually changes at the first pose 403 and the second exposure dose that gradually changes at the second pose 404, the rotation angle of the grating structure of the two-dimensional grating finally obtained on the exposure substrate will be different along the first direction and the second direction. Moreover, after the first exposure dose at the first pose 403 and the second exposure dose at the second pose 404 are superimposed on each other, the total exposure dose at different coordinate positions on the exposure substrate also has a certain change trend, so that the duty cycles of the multiple grating structures of the two-dimensional grating obtained on the exposure substrate are also different along the first direction and the second direction.

[0039] Exemplarily, let the exposed substrate at the second pose 404 be a two-dimensional grating obtained by rotating the exposed substrate at the first pose 403 clockwise by 90° and then translating it. Since only the first exposure dose used for exposure in the first direction at the center coordinate of the exposed substrate is equal to the second exposure dose used for exposure in the second direction, and the first exposure dose used for exposure in the first direction at other coordinate positions on the exposed substrate is not equal to the second exposure dose used for exposure in the second direction, the rotation angles of the formed two-dimensional grating in the first direction and the second direction are different, and are consistent with the change trends of the first exposure dose and the second exposure dose, and also have a spatially gradual change trend; further, the total exposure dose after superimposing the first exposure dose used for exposure in the first direction and the second exposure dose used for exposure in the second direction is also different in the first direction or the second direction, so the duty cycles of the formed two-dimensional grating in the first direction and the second direction are also different, and are consistent with the change trends of the first exposure dose and the second exposure dose, and also have a spatially gradual change trend. Exemplarily, please refer to Figure 7 , Figure 7 shows a schematic diagram of the grating structure of a two-dimensional grating formed by exposure on an exposed substrate in an embodiment of the present application. Among them, Figure 7 the placement pose of the exposed substrate 402 shown is the first pose, and the exposed substrate at the second pose 404 is a two-dimensional grating obtained by rotating the exposed substrate at the first pose 403 clockwise by 90° and then translating it. It can be seen that the duty cycles and rotation angles of the grating structure on the exposed substrate are different at different positions, and have a certain gradual change trend in the first direction or the second direction. Among them, it should be noted that the total exposure dose at the center position on the exposed substrate is the lowest after superimposing the first exposure dose in the first direction and the second exposure dose in the second direction. And the low exposure dose causes only a small part of the photoresist on the substrate to be exposed and eliminated, so the remaining solid structure is larger (the shaded area shown in the figure), making it present a structure different from the grating structure under high exposure dose exposure.

[0040] It can be understood that in such an interference exposure field, only by changing the relative pose of the exposed substrate in the interference exposure field, the first exposure dose in the first pose and the second exposure dose in the second pose can be changed. At the same time, still, the first exposure dose in the first pose and the second exposure dose in the second pose can be further changed by directly changing the central exposure power of the interference exposure field, so as to realize the gradient modulation of the structural parameters of the two-dimensional grating. Exemplarily, the interference exposure field is formed by the interference of two or more coherent light beams. When the coherent light is a Gaussian spot, the exposure power of the interference exposure field formed by its interference presents a Gaussian distribution from the center point to the radial direction. The method of directly changing the central exposure power of the interference exposure field can be achieved by modulating the amplitude of the coherent light.

[0041] As an implementation manner, before exposing the exposure substrate along the second direction using the interference exposure field with the second exposure dose, the interference exposure system can be used to translate or rotate the exposure substrate, so that the exposure substrate is displaced from the first pose to the second pose.

[0042] Therefore, for a two-dimensional grating preparation method provided in this application, when the exposure substrate is in the first pose, the first exposure dose at at least one exposure position is variable when the interference exposure field exposes the exposure substrate along the first direction. When the exposure substrate is in the second pose, the second exposure dose at at least one exposure position is also variable when exposing the exposure substrate along the second direction. Further, the first exposure dose has a decreasing or increasing change trend in the first direction, and the second exposure dose has a decreasing or increasing change trend in the second direction. That is to say, when exposing the exposure substrate, the exposure doses used along the first direction and the second direction have a gradual change trend and can be adjusted, so as to realize the modulation of the grating parameters of the two-dimensional grating along the first direction and the grating parameters along the second direction, making it show a gradual change trend consistent with the change trend of the exposure dose.

[0043] Please refer to Figure 8 , Figure 8 FIG. shows a schematic structural diagram of an interference exposure system provided by an embodiment of this application. Specifically, the interference exposure system includes: an exposure substrate 110, a light source 120, and an interference exposure component 130. Among them, the interference exposure component 130 is used to execute the method described in the above embodiment.

[0044] As an implementation manner, the interference exposure component 130 includes a mechanical motion component 101, a beam splitter 102, a first mirror 103, and a second mirror 104. Specifically, the light source 120 is configured to emit a first coherent light L1 and a second coherent light L2. The light beam L is incident on the beam splitter 102 after being modulated by the spatial light modulator 101 and is split by the beam splitter 102. A part of the first coherent light L1 and the second coherent light L2 is reflected by the first mirror 103 and then directed towards the exposure substrate 110, and another part of the first coherent light L1 and the second coherent light L2 is reflected by the second mirror 104 and also directed towards the exposure substrate 110. The first coherent light L1 and the second coherent light L2 interfere on the exposure substrate to form an interference exposure field. According to the above embodiment, when the light beam emitted by the light source 120 is a Gaussian spot, the exposure power of the interference exposure field formed by the first coherent light L1 and the second coherent light L2 on the exposure substrate is Gaussian-distributed along the radial direction from the center point. The mechanical motion component 101 is connected to the exposure substrate 110, and the mechanical motion component 101 is configured to translate or rotate the exposure substrate 110 so that the exposure substrate 110 can be displaced from the first pose to the second pose. Therefore, the interference exposure system provided in this embodiment can be used to prepare a two-dimensional grating with varying grating structure parameters.

[0045] Optionally, the interference exposure component 130 is further configured to adjust the magnitude of the first exposure dose or the second exposure dose to adjust the structural parameters of the two-dimensional grating.

[0046] Optionally, the structural parameters of the two-dimensional grating include a duty cycle parameter, and the interference exposure component 130 adjusts the total magnitude of the first exposure dose and the second exposure dose to adjust the duty cycle parameter of the two-dimensional grating.

[0047] Optionally, the structural parameters of the two-dimensional grating include a rotation angle parameter, and the interference exposure component 130 adjusts the first exposure dose or the second exposure dose to adjust the rotation angle parameter of the two-dimensional grating.

[0048] As an implementation manner, the interference exposure system further includes a spatial light modulator 140. The spatial light modulator 140 is configured to modulate the exposure power distribution of the interference exposure field. Specifically, the spatial light modulator 140 can modulate the amplitude of the light beam L to change the exposure power distribution of the interference exposure field.

[0049] As an implementation manner, the interference exposure system can be such as Figure 8The double-beam interference exposure system shown. In the double-beam interference exposure system, to obtain a two-dimensional grating, it is necessary to perform one exposure in one direction and then a second exposure in another orthogonal direction. Therefore, for a double-beam exposure system, the method of obtaining a two-dimensional grating with gradually changing grating parameters can be achieved by spatially modulating the amplitude of the light beam to change the exposure dose of the interference exposure field when the exposure substrate is in the first pose, or / and by changing the exposure dose of the interference exposure field when the exposure substrate is in the second pose. Alternatively, it can also be achieved by only changing the spatial relative pose between the exposure substrate and the interference exposure field in an interference exposure field where the exposure power is Gaussian-distributed along the radial direction from the center point.

[0050] As an implementation, the interferometric exposure system can also be a three-beam interferometric exposure system. In the three-beam exposure system, the preparation of a two-dimensional grating structure can be directly achieved in one exposure. Therefore, the ratio of the exposure doses of the interference exposure fields corresponding to different coordinates on the exposure substrate can be modulated by directly modulating the optical power distribution of the three coherent light beams that form the interference exposure field, so as to modulate the grating structure parameters of the prepared two-dimensional grating.

[0051] Therefore, an interferometric exposure system provided in this application includes an exposure substrate, a light source, and an interference exposure component. The interference exposure component is configured to expose the exposure substrate along a first direction with a first exposure dose through the interference exposure field when the exposure substrate is in the first pose; and expose the exposure substrate along a second direction with a second exposure dose through the interference exposure field when the exposure substrate is in the second pose, so as to obtain a two-dimensional grating. Therefore, the first exposure dose and the second exposure dose of the interferometric exposure system provided in this application are different at at least one exposure position of the exposure substrate, so that the grating structure of the finally obtained two-dimensional grating corresponding to the exposure position has a rotation angle, so as to realize the preparation of a two-dimensional grating with changing grating structure parameters.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a two-dimensional grating, characterized in that, Applied to an interferometric exposure system, the interferometric exposure system includes an exposure substrate and a light source, the light source being used to form an interferometric exposure field, and the method includes: When the exposure substrate is in a first pose, exposing the exposure substrate along a first direction with a first exposure dose through the interferometric exposure field; When the exposure substrate is in a second pose, exposing the exposure substrate along a second direction with a second exposure dose through the interferometric exposure field to obtain a two-dimensional grating; Wherein, the first exposure dose and the second exposure dose of the interferometric exposure field at at least one exposure position of the exposure substrate are different, so that the grating structure of the two-dimensional grating corresponding to the exposure position has a rotation angle.

2. The method according to claim 1, characterized in that Before exposing the exposure substrate along the first direction with the first exposure dose through the interferometric exposure field when the exposure substrate is in the first pose, the method further includes: Adjusting the magnitude of the first exposure dose or the second exposure dose of the interferometric exposure field at at least one exposure position of the exposure substrate to adjust the structural parameters of the grating structure of the two-dimensional grating corresponding to the exposure position.

3. The method according to claim 2, characterized in that, The structural parameters include a duty cycle parameter, and adjusting the magnitude of the first exposure dose or the second exposure dose of the interferometric exposure field at at least one exposure position of the exposure substrate to adjust the structural parameters of the grating structure of the two-dimensional grating corresponding to the exposure position includes: Adjusting the total magnitude of the first exposure dose and the second exposure dose of the interferometric exposure field at at least one exposure position of the exposure substrate to adjust the duty cycle parameter of the grating structure of the two-dimensional grating corresponding to the exposure position.

4. The method according to claim 2, characterized in that, The structural parameters include a rotation angle parameter, and adjusting the magnitude of the first exposure dose or the second exposure dose of the interferometric exposure field at at least one exposure position of the exposure substrate to adjust the structural parameters of the grating structure of the two-dimensional grating corresponding to the exposure position includes: Adjusting the ratio of the first exposure dose to the second exposure dose of the interferometric exposure field at at least one exposure position of the exposure substrate to adjust the rotation angle parameter of the grating structure of the two-dimensional grating corresponding to the exposure position.

5. The method according to claim 2, wherein Adjusting the magnitude of the first exposure dose or the second exposure dose of the interferometric exposure field at at least one exposure position of the exposure substrate includes: Adjusting the exposure power distribution and exposure time of the interferometric exposure field to adjust the magnitude of the first exposure dose or the second exposure dose of the interferometric exposure field at at least one exposure position of the exposure substrate.

6. The method according to claim 1, characterized in that The center point of the interferometric exposure field has the highest exposure power, and the exposure power of the interferometric exposure field is distributed in a Gaussian manner radially from the center point; Wherein, the first direction and the second direction are orthogonal, the interferometric exposure field has a first exposure dose that weakens or strengthens along the first direction at the first pose, and the interferometric exposure field has a second exposure dose that weakens or strengthens along the second direction at the second pose.

7. The method according to claim 1, wherein Before obtaining a two-dimensional grating by exposing the exposure substrate in a second exposure dose along a second direction through the interference exposure field when the exposure substrate is in a second pose, the method further includes: Translating or rotating the exposure substrate to displace the exposure substrate from the first pose to the second pose.

8. An interference exposure system, characterized in that, Comprising an exposure substrate, a light source, and an interference exposure assembly, the light source is used to form the interference exposure field, and the interference exposure assembly is used to perform the method according to any one of claims 1-7.

9. The interferometric exposure system according to claim 8, wherein: The system further includes a spatial light modulator, and the spatial light modulator is used to adjust the exposure power distribution of the interference exposure field.

10. A two-dimensional grating, characterized in that, The two-dimensional grating is manufactured based on the method according to any one of claims 1-7, and the duty cycle parameter and the rotation angle parameter of the two-dimensional grating along the first direction are different from each other, and the duty cycle parameter and the rotation angle parameter of the two-dimensional grating along the second direction are different from each other.

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